[USRP-users] Receiving problem with USRP N210

Marcus Müller marcus.mueller at ettus.com
Wed Oct 15 13:28:24 EDT 2014


Glad things worked out for you!


On 15.10.2014 19:16, Su Li wrote:
> Hi Marcus,
>
> Thank you very much.
>
> Following your suggestions, I found the problem that I forgot to configure
> the antenna port. Since I only have one antenna, I thought it would
> automatically choose that one. But in fact, I still have to configure it as
> TX/RX.
>
> Best regards,
>
> Su
>
>
>
> 2014-10-15 18:47 GMT+02:00 Marcus Müller <usrp-users at lists.ettus.com>:
>
>>  Hello Su Li,
>>
>> just a few general RF engineering debugging approaches:
>>
>> * check your measurement set up. Is it the right antenna for this
>> frequency range, attached to the right port (believe me, I mistakenly used
>> the wrong port quite a couple of times), at the right receiving
>> bandwidth/sampling rate, with a feasible gain? If you don't risk damaging
>> your device, crank up the gain!
>> * A scope sink can impossibly show you fast bursty signals; if you know
>> your spectral shape (eg. it's GMSK with a 3dB bandwidth of 200kHz, or it's
>> 10MHz wide OFDM or so), use the waterfall sink. It will give you some more
>> long-time visual impression. Generally, any frequency domain sink will most
>> probably be better suited than using the scope sink.
>> * If that signal is spread-spectrum, you might not notice anything at all
>> looking at the spectrum or time domain signal at all. I don't know this
>> specific system, and I must admit it's a bit much asking for help without
>> giving us a few edge parameters to guess from ;)
>> * If you happen to know the pulse shape, implement a matched filter. You
>> seem to have a software sender -- so you should have the possibility to get
>> to know that shape. If the pulse shaping is in fact done by a FIR, you
>> could just take the taps and use their time-reversed conjugate as the
>> matched filter. That should give you some processing gain :)
>>
>> Greetings,
>> Marcus
>>
>>
>> On 15.10.2014 17:02, Su Li via USRP-users wrote:
>>
>> Hi,
>>
>> I have an USRP N210 with RFX2400 2.3-2.9GHZ RX/TX. I am trying to build a
>> communication link between Tmote sky wireless sensor node and USRP N210.
>>
>> I use Tmote sky node to repeatedly broadcast messages on radio channel 26
>> with power level 31 (=0dBm). The code I use is the example code of Contiki
>> and I can receive this broadcast message by a receiver implemented by a
>> Tmote sky node.
>>
>> However, I cannot receive the message on USRP N210. When I tried to check
>> the signal that the antenna received, I found nothing except the noise. In
>> GNU radio companion, I just used a UHD-USRP Source with frequency at
>> 2.48GHz to get the signal from USRP and check them in a  Scope sink. I
>> thought the power of the received signal would increase a lot when the
>> sensor node broadcast messages. But I did not see a large increment of the
>> amplitude of the signal. I also tried using trigger to catch the burst
>> spike, but I failed.
>>
>> Anyone can give me some suggestions to fix this problem?
>>
>> Thanks in advance.
>>
>> Best regards,
>> Su
>>
>>
>>
>>
>> _______________________________________________
>> USRP-users mailing listUSRP-users at lists.ettus.comhttp://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>>
>>
>>
>> _______________________________________________
>> USRP-users mailing list
>> USRP-users at lists.ettus.com
>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>>
>>





More information about the USRP-users mailing list